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Thermodynamic understanding the phase behavior of fully quaternized poly(ethylene oxide)-b-poly(4-vinylpyridine) block copolymers
Polymer ( IF 4.6 ) Pub Date : 2022-06-09 , DOI: 10.1016/j.polymer.2022.125045
Ze-Kun Zhang, Shi-Peng Ding, Ze Ye, Ding-Li Xia, Jun-Ting Xu

In this study, the poly(ionic liquid)s (PILs)-based block copolymers (BCPs) with a high charge density, poly(ethylene oxide)-b-quaternized poly(4-vinylpyridinium) with X as counterion (PEO-b-QP4VP-X), were prepared by full quaternization of the poly(4-vinylpyridine) (P4VP) block in neutral PEO-b-P4VP BCP. The complete quaternization of P4VP block was confirmed by NMR and FT-IR. The phase separation behavior of PEO-b-QP4VP-X BCPs was examined, which was found to be strongly dependent on the counterion species. Specifically, as compared with the neutral PEO-b-P4VP, PEO-b-QP4VP-Br exhibits a stronger segregation strength, while the other three PEO-b-QP4VP-X (X = PF6, TFO and TFSI) BCPs show a weaker phase separation ability. The phase behavior of PEO-b-QP4VP-X was explained using the thermodynamic mechanism originally applied for salt-doped BCPs of low charge density. The variation of the Flory-Huggins parameter (Δχ) can be divided into three terms: Δχ1 due to the change in monomer identity after quaternization, ΔχBorn from the Born energy of counterions and χΓ arising from the local charge cohesion. For PEO-b-QP4VP-X BCPs, both Δχ1 and ΔχBorn are negative, but χΓ is positive, and they vary with counterion size in different ways. The competition of these three terms dominates the change tendency of phase behavior, among which Δχ1 plays an important role at high level of charge density. The rationality of the aforementioned thermodynamic mechanism of Δχ was also verified by the phase behavior of salt-doped PEO-b-QP4VP-X.



中文翻译:

热力学理解完全季铵化聚(环氧乙烷)-b-聚(4-乙烯基吡啶)嵌段共聚物的相行为

在本研究中,基于聚(离子液体)(PILs)的嵌段共聚物(BCPs)具有高电荷密度,聚(环氧乙烷)- b-季铵化聚(4-乙烯基吡啶鎓),X -作为抗衡离子(PEO- b -QP4VP-X),通过在中性 PEO-b-P4VP BCP 中对聚 (4-乙烯基吡啶) (P4VP) 嵌段进行完全季铵化制备。通过 NMR 和 FT-IR 确认 P4VP 嵌段的完全季铵化。检查了 PEO- b -QP4VP-X BCP的相分离行为,发现其强烈依赖于反离子种类。具体而言,与中性 PEO- b -P4VP 相比,PEO- b -QP4VP-Br 表现出更强的偏析强度,而其他三种 PEO-b -QP4VP-X (X = PF 6 , TFO 和 TFSI) BCP 表现出较弱的相分离能力。使用最初应用于低电荷密度盐掺杂 BCP 的热力学机制解释了 PEO- b -QP4VP-X的相行为。Flory-Huggins 参数的变化 (Δ χ ) 可以分为三项:Δ χ 1由于季铵化后单体同一性的变化,Δ χ Born来自反离子的 Born 能量和χ Γ来自局部电荷凝聚力. 对于 PEO- b -QP4VP-X BCP,Δ χ 1和 Δ χ Born均为负值,但χ Γ为正,它们随反离子大小以不同方式变化。这三项的竞争主导了相行为的变化趋势,其中 Δ χ 1在高电荷密度下起重要作用。上述Δχ热力学机制的合理性也通过盐掺杂PEO- b - QP4VP -X的相行为得到验证。

更新日期:2022-06-13
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